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This invention refers to an integrating device to detect, recover and compensate the deformation of shoulders, in a press-bending machine.
The innovation finds particular even if not exclusive application in the field of machine tools.
Press-bending machines, as known, are widely used in the engineering industry, and particularly in the working of metal sheets, to obtain, for example, differently shaped longitudinal sections, sometimes with the possibility of being each re-taken and subjected again to a cycle of press-bending.
Operatively, a press-bending cycle consists in the vertical descent of a tool, until it presses on the underlying metal sheet rested on the matrix, in carrying out the bending, and then, at the end, in proceeding with the ascent, up to a primary position. For carrying out the mentioned steps, the machine consists of two parts, respectively a first one, dynamic, generally engaging the upper part, and a substantially static part, constituting the underside of the machine placed perpendicular to the dynamic part. As far as the first dynamic part is concerned, in the execution of a press-bending cycle, a tool is provided for, made up of a differently shaped punch, also of the interchangeable type, which, supported by a beater or upper cross-piece, makes just one movement, along a vertical axis, of to and fro. The said movement is ensured by at least two oil-dynamic end-cylinders, which determine the descent, the possible stop and ascent of the beater that supports the tool longitudinally. Every cylinder group, in a traditional forming press, is joined and made integral with the frame or static body of the machine, and, in this case, to a corresponding side or side-shoulder of the frame of the press.
These characteristics give origin, during the pressing phase, to a multitude of rather strong forces, which develop in various known directions to engage the different parts of the machine, deforming them temporarily. Furthermore, some of these forces above all, end up modifying the shape of each shoulder even in a non-uniform way. It follows that during the execution phase of a press-bending cycle, a widespread deformation takes place, which affects in a negative way the qualitative result of the working required.
Tests carried out on the test stand, have evidenced that this characteristic temporary deformation of each shoulder, has its own logical progression the more the punch presses down on the sheet, and it is always proportional to the thickness of the sheet and to the type of material.
It therefore follows that it is necessary to have a control system that allows to detect the deflection of the shoulders, in order to intervene in the first stages of the working process. Then it is a question of correctly prearranging the forming press, in order that it can carry out a manufacturing cycle that will allow to achieve the predetermined bending angle with precision.
Actually, two techniques are known for solving the problem, which however do not seem completely satisfactory.
In one case, the movement of the beater or punch carrying cap of the synchronized bending presses is given by two hydraulic cylinders, placed to the sides of the first and integral with the shoulders, which assume the name of the two axes. These axes, are checked sideways by optical rulers where a small reading trolley slides. The reading trolley is hinged, through a rod, to the upper end of a flexion recovery shoulder or false shoulder, superimposed to the shoulder, which is made integral, only on the underside, with the cross-piece, with the platform and with the matrix.
Considering the fact that the false shoulder is integral with the cross-piece, with the platform and with the matrix, the punch should, both when under pressure and when load-less, maintain a locating spot in correspondence with the bottom dead center. Intuitively, this should take place because the false shoulder is not engaged to the shoulder.
A second system, not shown, but just as common, is the solution originally suggested by the Beyler Company. It refers to an electronic card consisting of a data base, cooperating with the logical unit of the machine, where a great number of data relative to the known deformations is stored, therefore including the deformation of shoulders, in relation to an entire series of parameters, namely: extension of the carpentry, extension of optical lines, changes on the viscosity of the oil, electric de-compensations, de-compensations in the control of the valves. This data have been previously acquired on the basis of a series of tests and subsequently transferred to the database. The processing and the comparing of these by a logical unit with others values, allows to define, in a manufacturing cycle of the sheet, ascribable theoretic values foreseeable in the localized deformation of the shoulders that therefore will be conveniently recovered.
Therefore there is the need for companies to find alternative and more effective systems than the ones described above.
A purpose of the present proposal is also to avoid the abovementioned drawbacks.
This and other purposes are achieved with this innovation according to the characteristics as in the included claims, solving the mentioned problems, with an integrating device to detect and recover the deformation of shoulders, in a press-bending machine, including an optical ruler joined to the beater and a reading trolley, pulled back elastically, stressed by the false shoulder; said device provided for above the false shoulder, being made up of a rod placed perpendicular to the beater, which is hinged to the shoulder of the machine on one side, while the opposite end, oscillating and directed towards said beater, is stressed by the arm joined to the reading trolley of the optical ruler, and furthermore in which said rod provides a sliding device in correspondence with an underlying plane plate that is part of the false shoulder.
The considerable creative contribution, found in the proposal now described, determines an immediate technical progress, allowing to obtain various advantages.
First of all, the system gives the user the possibility of finding the desired angle in a fast way, with intuitable and extremely simple operations. More particularly, first it carries out tests on a small piece to then take it on to a definite piece, even along the total length of the machine or differently placed along the fold-line (right, left and center). All this independently of the bending force, that, as known, varies according to what piece has to be bent.
Secondly, this system has the advantage of correcting automatically the different flexions noticeable from one shoulder to the other, caused by variations in the thickness of the material with which the shoulders are obtained, by the diversity of the materials, as well as by continuous variations in the temperature of the environment where the said machine is made operative.
Amongst the peculiarities of this invention, it is important to point out the fact that, under the executive point of view, having two metal-sheets of the same length but with a different bending section, the result between the two pieces is maintained constant.
An additional advantageous point refers to the lack of particular complications in the device; this implies almost an absence of maintenance with rather low costs, relatively to the construction and to installation. The particularity of the device, additionally, also allows installations on already existing machines, favoring an increase in quality and, as a whole, in the works in progress.
These advantages have the all but negligible value of obtaining a product with a good technological content, functional and extremely reliable, even if submitted to particular working conditions.